Prior to the study, they knew that birds experience two phases of sleep -- slow wave sleep (SWS) and rapid eye movement (REM) -- just like mammals do.

SWS is deep, dreamless sleep during which the brain shows synchronous, slow oscillations of neurons as shown on an EEG (electroencephalogram). SWS alternates with dreaming sleep, called REM (rapid eye movement) because the eyes move rapidly during this period even though the lids are closed.

To study sleep in pigeons researchers prevented the birds from taking naps, something they like to do late in the day. (I do too!)

The pigeons were allowed to sleep normally at night when researchers learned that the birds made up for their sleep loss by more intense periods of SWS. Their slow-wave-sleep lasted the same amount of time as before but during SWS the number of slow waves was much higher. In other words, they slept more deeply.

Mammals do this too under similar conditions. We all "power sleep" when especially tired.

Well from my deck they may dream of filled bird feeders!!! I have now been power sleeping & it probably works. Don’t sleep well at night but during the day I fall asleep & when I waken I think its been an hour & clock says only 20 minutes & I do feel better so maybe that’s a good thing. Never thought about birds & sleep. When you watch the nests we see that the young ones sleep on their stomachs & are so relaxed. Interesting topic today.